, Volume 11, Issue 1, pp 23–28 | Cite as

X-ray energies for effective atomic number determination

  • R. A. Rutherford
  • B. R. Pullan
  • I. Isherwood


The measurement of the effective atomic number of a piece of material in vivo can be achieved using computed tomography. The precision of measurement of this parameter depends on the precision of measurement of the X-ray absorption coefficient at two energies and the separation of these energies. With the assumption of a fixed photon flux, it is shown that two optimum energies exist for the measurement of effective atomic number. The analysis indicates that if energies of 40 keV and 80 keV are employed, a precision of at least 1 part in 400 in the measurement of effective atomic number may be achieved.

Key words

Computed tomography EMI scanner Effective atomic number Linear absorption coefficient 


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  1. 1.
    Rutherford, R. A., Pullan, B. R., Isherwood, I.: Measurement of Effective Atomic Number and Electron Density using an EMI Scanner. Neuroradiology 11, 15–21 (1976)Google Scholar
  2. 2.
    Hubbell, J. H.: Photon cross sections, attenuation coefficients, and energy absorption coefficients from 10 keV to 100 GeV. NSRDS-NBS 29, Washington: U. S. Government Printing Office 1969Google Scholar
  3. 3.
    EMI Ltd., Hayes, Middlesex: Personal CommunicationGoogle Scholar
  4. 4.
    Bracewell, R. N., Riddle, A. C.: Inversion of fan-beam scans in Radio Astronomy. Astrophysical J. 150, 427–434 (1967)Google Scholar
  5. 5.
    Crowther, R. A., Derosier, D. J., Klug, A.: The reconstruction of a three-dimensional structure from projections and its application to electron microscopy. Proc. Roy. Soc. Lond. A. 317, 319–340 (1970)Google Scholar
  6. 6.
    Ramachandran, G. N., Lakshminarayanan, A. V.: Three-dimensional reconstruction from radiographs and electron micrographs: application of convolutions instead of Fourier transforms. Proc. Nat. Acad. Sci. U.S.A. 68, 2236–2240 (1971)Google Scholar
  7. 7.
    Gilbert, P. F. C.: The reconstruction of a three-dimensional structure from projections and its application to electron microscopy II. Direct methods. Proc. Roy. Soc. Lond. B. 182, 89–102 (1972)Google Scholar
  8. 8.
    Hoffman, E. J., Phelps, M. E.: Production of monoenergetic X-rays from 8 to 87 keV. Phys. Med. Biol. 19, 19–35 (1974)Google Scholar

Copyright information

© Springer-Verlag 1976

Authors and Affiliations

  • R. A. Rutherford
    • 1
  • B. R. Pullan
    • 1
  • I. Isherwood
    • 2
  1. 1.Department of Medical BiophysicsUniversity of ManchesterEngland
  2. 2.Department of Diagnostic RadiologyUniversity of ManchesterEngland

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